Dell OptiPlex 7040-Small Form Factor Owner's Manual page 19

4. To remove the PSU:
a. Disconnect the power cable from the system board [1] [2].
b. Lift the cables away from the computer [3].
c. Remove the screws that secure the PSU to the computer [4].
5. Press the blue release tab [1], slide the PSU and lift it away from the computer [2].
Removing and installing components 19